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Welcome to the Valles Marineris Wildlife Park!

From
Charles Joynson, Rayleigh, Essex, UK

Sarah Moles notes that it is hard to decide which species to save with limited resources (Letters, 4 February). But if our longer term future includes terraforming other planets, then we will have to take other species with us as DNA, rather than as live and potentially dangerous fellow passengers. So the question for us now is: what to save that allows us to resurrect something in the future?

The options include saving a species in the wild, in a zoo, in frozen form or as a DNA sequence. The more of them we save, the more likely it is we could give each a place in future. But if we tried to resurrect an extinct mammal, would we be able to restore its genetic diversity, as well as its gut and skin microflora? And what about the rest of its ecosystem?